Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 
New Member

Access Point to ACS Authentication

Attempting to setup wireless users to authenticate through new ACS 3.1 server. With our test user we are getting an error message in the 'Failed Attempts Log' that we can't find and explanation for to see what it means.

In the Authentication Failure code field...

Radius Extension DLL rejected user

Any pointer towards an explanation for this message would be appreciated!

We do see the MAC of the 350 card in the Username and Caller-ID fields.

Cisco Employee

Re: Access Point to ACS Authentication

Radius Extention DLL rejected means radius is not able to authenticate the


a) Turn on debugging on ACS and generate file for more troubleshooting .

b) Make sure there is ip connectivity between ACS and AP . Can you ping AP from the ACS ?

c) Make sure you have defined AP as NAS client on the ACS and also make

sure SHARED SECRET is correct on AP and on ACS .

d) Make sure you are using right ports , 1645 or 1812 .....

e) Make sure user is created and entering the right passowrd .

f) If you are not using local database and using some external database

check the connectivity with external database and try local user first

g) On Ap you can turn on the command like



to make it off use

eap_diag1_off and eap_diag2_off

this is only in case of AP350 and Ap1200 .

h) when you put AP as nas client on ACS select correct radius type - Cisco Aironet


New Member

Re: Access Point to ACS Authentication

Thanks, we'll give those a try....

A followup, We don't find the Add Access Server under ACS Network Configuration as the doco says we should. We've got Add a Client, Add an AAA server, and Proxy Distribution Table.

New Member

Re: Access Point to ACS Authentication

Dear Noshi,

I’m trying to configure a Cisco AP340 11.07 authenticating users using EAP protocol onto our ACS 3.0 to a W2K domain external database. I had checked all the points that you mention that can be applied to my case, but I still get the same error “Radius Extension DLL rejected”. I can use an account in the Local ACS’s DB or from the domain, the ACS recognises even the group the user is in, but still gives me this error.

From what I had read, the versions of AP and ACS should work. Any ideas or suggestions?

Many Thanks

CreatePlease to create content